Early strength enhancement of cements

ABSTRACT

A method of making a cement composition, comprising grinding a cement clinker and a strength-enhancing agent, thereby producing a hydraulic cementitious powder, wherein the strength-enhancing agent is present in the hydraulic cementitious powder in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder. The strength-enhancing agent is a compound represented by the following structural formula (I). The definitions of variables R1, R2, and R3 as well as R10, R20, and R30 are provided herein.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/458,380, filed on Feb. 13, 2017 and U.S. Provisional Application No. 62/508,636, filed on May 19, 2017. The entire teachings of the above applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

For cementitious compositions such as ready-mix, precast, or prestress concrete, for which it is desired to expedite manufacture or to obtain a concrete that can be subjected quickly to foot or car traffic, the concrete industry has prized the ability to obtain early compressive strength. Early strength is also important for applications that use bagged cements because it allows the users to obtain a minimum strength. The industry typically refers to early strength in terms of the compressive strength of the mortar and concrete within 1-3 days after mixing the cementitious material with water to initiate the curing reaction by which the composition hardens into a structure. Optimizing the compressive strength of hydraulic cementitious materials through the use of chemical admixtures has been studied in the engineering and chemical arts. While early strength cements are available, they are not always suitable for a particular task. Furthermore, certain chemical additives can impart undesirable characteristics to the cement. As such, there is a need for a chemical additive for hydraulic cementitious materials that can increase early compressive strength.

SUMMARY OF THE INVENTION

It has now been discovered that certain amino acid derivatives that include a carboxyl group (in either acid or salt form) and an alcohol group, such as ethanol diglycinate (EDG), surprisingly imparts early strength to certain cement compositions comprising hydraulic cementitious materials. In example embodiments, the hydraulic cementitious materials are preferably characterized by having not more than 9% tricalcium aluminate (C₃A) content.

In the first example embodiment, the present invention is a method of making a cement composition. The method comprises grinding a cement clinker and a strength-enhancing agent, thereby producing a hydraulic cementitious powder. The strength-enhancing agent is present in the hydraulic cementitious powder in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder. The strength-enhancing agent is a compound represented by the following structural formula:

wherein R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, is (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, or K⁺. In one example embodiment, R* is H, Na⁺, K⁺, or ½ Ca⁺⁺.

In a further aspect of the first example embodiment, the cement clinker includes tricalcium aluminate (C₃A) in an amount of 0.3% to 9.0% based on dry weight of cement clinker. The content of the total aluminate phase (C₃A) can be determined by quantitative X-ray diffraction using the Rietveld refinement method.

In another example embodiment, the present invention is an additive composition, comprising (A) a strength-enhancing agent described above with reference to the first embodiment; and (B) at least one grinding aid selected from one or more of a glycol, glycerin, or acetic acid or an acetic acid salt. In one aspect, the additive composition is a liquid.

In another example embodiment, the present invention is a cement composition, comprising a hydraulic cementitious powder that includes tricalcium aluminate (C₃A) in an amount of from 0.3% to 9.0% based on dry weight of the hydraulic cementitious powder; a strength-enhancing agent present in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder; at least one grinding aid selected from a glycol, glycerin, or acetic acid or a salt thereof. The strength-enhancing agent is a compound described above with reference to the first example embodiment.

The strength-enhancing agents described herein possess important advantages in addition to early strength enhancement. For example, while some strength-enhancing agents will cause iron staining in finished cementitious products due to iron chelation in the cement pore water, the cement compositions described herein do not cause iron staining. The agents described herein can also be used as grinding aids in the cement manufacturing process, resulting in cements having a higher specific surface area.

In another example embodiment, the strength-enhancing agent suitable for use with the methods and compositions of the present invention is made by a process comprising: reacting a monohaloacetic acid chosen from monochloroacetic acid and monobromoacetic acid, or a salt thereof, with a alkanolamine chosen from ethanolamine, isopropanolamine, and isobutanolamine under alkaline conditions to generate the strength-enhancing agent represented by the structural formula

wherein R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, represent —CH₂COOR* wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺

In another example embodiment, the present invention is a method of making a strength-enhancing agent and a strength-enhancing agent made by the method, comprising: reacting a haloacetic acid chosen from one or more of a chloroacetic acid and a bromoacetic acid, or a salt thereof, with one or more alkanolamines of the structural formula (I)

under alkaline conditions, to generate the strength-enhancing agent represented by structural formula (II)

wherein:

each R¹⁰ is independently chosen from H, (C₁-C₄)alkyl-OH, provided that in structural formula (I) at least one group R¹⁰ is not H;

R²⁰ is chosen from (C₁-C₄)alkyl-OH, and —C(R⁴)₂COO⁻M⁺; and R³⁰ is —C(R⁴)₂COO⁻M⁺; each R⁴ is independently chosen from hydrogen, Br, and Cl; and M⁺ is H⁺, Na⁺, K⁺, or ½ Ca⁺⁺.

In another example embodiment, the present invention is an additive composition, comprising: a first component; and a cement additive component. The cement additive component is one or more agent chosen from a glycol, glycerol, acetic acid or a salt thereof, an alkanolamine, an amine, a carbohydrate, a water-reducing additive, an air-entraining agent, a chloride salt, a nitrite salt, a nitrate salt, and a thiocyanate salt; and the first component is prepared by reacting a haloacetic acid chosen from one or more of a chloroacetic acid and a bromoacetic acid, or a salt thereof, with one or more alkanolamines of the structural formula (I)

under alkaline conditions, to generate the first component represented by structural formula (II)

wherein each R¹⁰ is independently chosen from H, (C₁-C₄)alkyl-OH, provided that in structural formula (I) at least one group R¹⁰ is not H; R²⁰ is chosen from (C₁-C₄)alkyl-OH, and —C(R⁴)₂COO⁻M⁺; and R³⁰ is —C(R⁴)₂COO⁻M⁺; each R⁴ is independently chosen from hydrogen, Br, and Cl; and M⁺is H⁺, Na⁺, K⁺, or ½ Ca⁺⁺.

In another example embodiment, the present invention is a concrete composition, comprising the additive composition described above; cement; a fine aggregate; a coarse aggregate, and at least one supplemental cementitious material chosen from fly ash, granulated blast furnace slag, limestone, calcined clay, natural pozzolan, and artificial pozzolan.

In another example embodiment, the present invention is a method of making a cement composition, comprising reacting a monohaloacetic acid chosen from monochloroacetic acid and monobromoacetic acid, or a salt thereof, with a alkanolamine chosen from ethanolamine, isopropanolamine, and isobutanolamine under alkaline conditions to generate the strength-enhancing agent represented by the structural formula

wherein:

R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, represent —CH₂COO⁻R*, thereby preparing a reaction mixture; adding the reaction mixture without purification to a cement clinker; and grinding the cement clinker and the reaction mixture, thereby producing a hydraulic cementitious powder.

The strength-enhancing agents described above, including the compounds manufactured by the above-described reaction of a haloacetic acid or a salt thereof with one or more alkanolamines, enhance early strength in cement, particularly when used as a grinding additive. The additive composition that include such strength-enhancing agents can be combined with one or more conventional grinding additive components, such as may be chosen from glycols, glycerols, acetic acid or salt thereof (e.g., sodium acetate), alkanolamines (e.g., triethanolamine, triisopropanolamine, diethanolisopropanolamine), amines (e.g., tetrahydroxylethylene diamine), carbohydrates, polycarboxylate ethers, air entraining agents, chlorides, nitrites, nitrates, thiocyanates, alkali sulfates, alkali carbonates, or mixture thereof, to provide an additive grinding composition providing value and flexibility to cement manufacturers.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.

FIG. 1 is a plot of a change (in percent relative to a control) of compressive strength of a cement sample at Day 1 post mortar preparation as a function of C₃A content. Na₂-EDG was added to the samples at 0.02% by weight of the cementitious material.

FIG. 2A is a plot of compressive strength (in MPa) of a cement A sample at Day 1 post mortar preparation as a function of the carboxyl functionality (COO—) content (expressed in parts-per-million relative to cement weight). The carboxyl functionality is provided by the listed additives.

FIG. 2B is a plot of compressive strength (in MPa) of a cement B sample at Day 1 post mortar preparation as a function of the content of the additive (in weight percent).

FIG. 3 is a plot of “volume fraction” of the particles in a ground cement sample as a function of particle size in micrometers. Filled circles indicate cement compositions that include 0.02% by weight Na₂-EDG additive; white squares—cement compositions without an additive.

FIG. 4A and FIG. 4B, collectively, represent Table 1 of Example 1.

FIG. 5, panel A, shows the NMR spectrum of Sample A, described in Example 6. FIG. 5, panel B, shows the NMR spectrum of Sample B, described in Example 6.

DETAILED DESCRIPTION OF THE INVENTION

A description of example embodiments of the invention follows.

The conventional cement chemist's notation uses the following abbreviations:

CaO═C

SiO₂═S

Al₂O₃=A

Fe₂O₃═F

Under this notation, the following abbreviations are used:

tricalcium silicate=C₃S

dicalcium silicate=C₂S

tricalcium aluminate=C₃A

tetracalcium aluminoferrite=C₄AF

As used herein, “alkyl” means an optionally substituted saturated aliphatic branched or straight-chain monovalent hydrocarbon radical having the specified number of carbon atoms. Thus, “(C₁-C₄) alkyl” means a radical having from 1-4 carbon atoms in a linear or branched arrangement. “(C₁-C₄)alkyl” includes methyl, ethyl, propyl, isopropyl, n-butyl and tert-butyl.

As used herein, “alkanolamine” means an alkyl, typically a C1-C6 alkyl, functionalized with at least one amino group and at least one hydroxyl group. Examples of alkanolamines include triethanolamine or TEA, diethanol isopropanolamine or DEIPA, and tri-isopropanolamine or TIPA (typically used as conventional grinding aids in cement production).

As used herein, the term “amino acid” refers to a compound having both an amino —NH₂ and a carboxy —CO₂H functionalities. The term includes both a naturally occurring amino acid and a non-natural amino acid. The term “amino acid,” unless otherwise indicated, includes both isolated amino acid molecules (i.e. molecules that include both, an amino-attached hydrogen and a carbonyl carbon-attached hydroxyl) and residues of amino acids (i.e. molecules in which either one or both an amino-attached hydrogen or a carbonyl carbon-attached hydroxyl are removed). The amino group can be alpha-amino group, beta-amino group, etc. For example, the term “amino acid alanine” can refer either to an isolated alanine H-Ala-OH or to any one of the alanine residues H-Gly-, -Gly-OH, or -Gly-. Unless otherwise indicated, all amino acids found in the compounds described herein can be either in D or L configuration or a mixture. The term “amino acid” includes salts thereof.

An amino acid can be modified with additional functional groups. Examples of the additional functional groups include additional amino groups, additional carboxyl groups, and hydroxyl groups. Such modified amino acids can be referred to as “amino acid derivatives.” Examples of such amino acid derivatives include amino acids that include two carboxyl groups and one alcohol group, such as ethanol diglycinate (EDG).

As used herein, “glycol” refers to any one of an alkyl polyol compounds formed by oligomerization or polymerization of an alkyl diol via an ether bond formation. In example embodiments, a glycol is a polymer or an oligomer of a C2-C4 alkyl diol. For example, a glycol suitable to be used in this invention includes diethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, or mixtures thereof. The term “glycol,” as used herein, can also refer to “glycol bottoms,” i.e. mixed glycols typically comprised of ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol, often with color and other impurities.

As used herein, the term “glycerin” refers to propane-1,2,3-triol, both in purified and in crude form. For example, “glycerin,” as used herein, can refer to a crude glycerin, such as a byproduct obtained in the manufacture of biodiesel.

As used herein, “acetic acid” refers to a compound having the structural formula CH₃COOH. Salts of acetic acid (acetate salts) include salts of the alkali metals (Group I of the periodic table, such as sodium and potassium), and salts of alkali-earth metals (Group II of the periodic table, such as Ca²⁺). Preferred among these are sodium, potassium, and calcium acetate.

As used herein, “gluconic acid” refers to the compound having the following structural formula:

Salts of gluconic acid include ammonium salts, alkali metal salts (sodium and potassium), alkali-earth metal salts (calcium), and salts of iron, zinc, and aluminum.

As used herein, “sucrose” refers to a disaccharide combination of the monosaccharides glucose and fructose with the formula C₁₂H₂₂O₁₁.

As used herein, “corn syrup” refers to syrup made from cornstarch, consisting of dextrose, maltose, and dextrins.

As used herein, “molasses” refers to thick, dark brown syrup obtained from raw sugar during the refining process.

As used herein, a “chloride salt” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of hydrochloric acid.

As used herein, a “thiocyanate salts” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of thiocyanic acid.

As used herein, a “nitrite salt” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of nitrous acid (HNO₂).

As used herein, a “nitrate salt” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of nitric acid (HNO₃).

As used herein, an “alkali sulfate” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of sulfuric acid (H₂SO₄).

As used herein, an “alkali carbonate” refers to an alkali metal (Group I of the periodic table, e.g., sodium or potassium) or an alkali-earth (Group II of the periodic table, e.g., calcium) salts of carbonic acid (H₂CO₃).

The term “amine,” as used herein, means an “NH₃,” an “NH₂R_(p),” an “NHR_(p)R_(q),” or an “NR_(p)R_(q)R_(s)” group. The term “amino”, as used herein, refers to a mono-, bi-, or trivalent radical of the amine. In either the amine or amino groups, R_(p), R_(q), R_(q) can each be a C1-C6 alkyl, optionally substituted with the one or more hydroxyl groups or amino groups. Examples of an amine include tetrahydroxylethylene diamine (THEED).

As used herein, the term “alkanolamine” refers to an amine or an amine in which one of the alkyl groups is substituted with the hydroxyl. Examples of alkanolamines include triethanolamine, triisopropanolamine, and diethanolisopropanolamine.

As used herein, the term “carbohydrate” refers to polysaccharide cement additives, usually used as cement retarders. Examples include celluloses, exemplified by carboxymethylated hydroxyethylated celluloses, gum arabic and guar gum. Gum arabic is a product of an acacia tree of tropical Africa and is entirely soluble in water. Guar gum is derived from the seed of an annual plant which is cultivated in India. These products consist mainly of a polysaccharide of galactose and mannose.

As used herein, the term “a haloacetic acid,” unless specifically indicated, refers to any one of mono-, di-, or tri-substituted acetic acid analogs, or a mixture thereof. For example, the “chloroacetic acid” refers to any one of the following compounds or a mixture thereof: Cl—CH₂—COOH, Cl₂CH—COOH, or Cl₃C—COOH.

As used herein, the phrase “under alkaline condition” refers to the reaction conditions where the pH of the reaction mixture is greater than 7.

As used herein, the phrase “room temperature” refers to the temperature of about 21 to 25° C.

The content of all components in the compositions described below is indicated relative to the dry weight of the composition.

The terms “cement composition” or “cementitious powder” is used herein to designate a binder or an adhesive that includes a material that will solidify upon addition of water (hydraulic cementitious material), and an optional additive. Most cementitious materials are produced by high-temperature processing of calcined lime and a clay. When mixed with water, hydraulic cementitious materials form mortar or, mixed with sand, gravel, and water, make concrete. The terms “cementitious material,” “cementitious powder,” and “cement” can be used interchangeably.

Cement compositions includes mortar and concrete compositions comprising a hydraulic cement. Cement compositions can be mixtures composed of a cementitious material, for example, Portland cement, either alone or in combination with other components such as fly ash, silica fume, blast furnace slag, limestone, natural pozzolans or artificial pozzolans, and water; mortars are pastes additionally including fine aggregate, and concretes are mortars additionally including coarse aggregate. The cement compositions of this invention are formed by mixing certain amounts of required materials, e.g., a hydraulic cement, water, and fine or coarse aggregate, as may be applicable for the particular cement composition being formed.

As used herein, the term “clinker” refers to a material made by heating limestone (calcium carbonate) with other materials (such as clay) to about 1450° C. in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix to form calcium silicates and other cementitious compounds.

As used herein, the term “Portland cement” include all cementitious compositions which meet either the requirements of the ASTM (as designated by ASTM Specification C150), or the established standards of other countries. Portland cement is prepared by sintering a mixture of components including calcium carbonate (as limestone), aluminum silicate (as clay or shale), silicon dioxide (as sand), and miscellaneous iron oxides. During the sintering process, chemical reactions take place wherein hardened nodules, commonly called clinkers, are formed. Portland cement clinker is formed by the reaction of calcium oxide with acidic components to give, primarily tricalcium silicate, dicalcium silicate, tricalcium aluminate, and a ferrite solid solution phase approximating tetracalcium aluminoferrite.

After the clinker has cooled, it is pulverized together with a small amount of gypsum (calcium sulfate) in a finish grinding mill to provide a fine, homogeneous powdery product known as Portland cement. Due to the extreme hardness of the clinkers, a large amount of energy is required to properly mill them into a suitable powder form. Energy requirements for finish grinding can vary from about 33 to 77 kWh/ton, depending upon the nature of the clinker. Several materials such as glycols, alkanolamines, aromatic acetates, etc., have been shown to reduce the amount of energy required and thereby improve the efficiency of the grinding of the hard clinkers. These materials, commonly known as grinding aids, are processing additives which are introduced into the mill in small dosages and interground with the clinker to attain a uniform powdery mixture. In addition to reducing grinding energy, the commonly used processing additives are frequently used to improve the ability of the powder to flow easily and reduce its tendency to form lumps during storage.

Clinker production involves the release of CO₂ from the calcination of limestone. It is estimated that for each ton of clinker produced, up to one ton of CO₂ is released to the atmosphere. The utilization of fillers such as limestone or clinker substitutes such as granulated blast furnace slags, natural or artificial pozzolans, pulverized fuel ash, and the like, for a portion of the clinker allow a reduction on the emitted CO₂ levels per ton of finished cement. As used herein, the term filler refers to an inert material that has no later age strength enhancing attributes; the term “clinker substitute” refers to a material that may contribute to long term compressive strength enhancement beyond 28 days. The addition of these fillers or clinker substitutes to form “blended cements” is limited in practice by the fact that such addition usually results in a diminution in the physical strength properties of the resultant cement. For example, when a filler, such as limestone, is blended in amounts greater than 5%, the resultant cement exhibits a marked reduction in strength, particularly with respect to the strength attained after 28 days of moist curing (28-day strength). As used herein, the term “blended cements” refers to hydraulic cement compositions containing between 2 and 90%, more conventionally between 5 and 70%, fillers or clinker substitute materials.

As used herein, the term “fine aggregate” refers to particulate material used in construction whose size is less than 4.75 mm. The term “coarse aggregate” refers to particulate material used in construction that is larger than about 2/16 inch.

In a first example embodiment, the present invention is a method of making a cement composition. The method comprises grinding a cement clinker and a strength-enhancing agent, thereby producing a hydraulic cementitious powder.

In a first aspect of the first example embodiment, the strength-enhancing agent is present in the hydraulic cementitious powder in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder. The strength-enhancing agent is a compound represented by the following structural formula:

wherein R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, is (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, and K⁺. In an example embodiment, R* is Na⁺, K⁺, or ½ Ca⁺⁺.

In a second aspect of the first example embodiment, the method of the first example embodiment further includes adding to the cement clinker at least one supplemental cementitious material selected from the group consisting of: fly ash, granulated blast furnace slag, limestone, calcined clay, natural pozzolans and artificial pozzolans.

In a third aspect of the first example embodiment, the cement clinker includes C₃A in the amount of 0.3% to 9.0%, for example, 0.3% to 7.0% based on dry weight of cement clinker. The content of the total aluminate phase (C₃A) can be determined by quantitative X-ray diffraction using the Rietveld refinement method.

In a fourth aspect of the first example embodiment, the method further includes grinding with the strength enhancement agent and the cement clinker at least one supplemental component selected from a grinding aid, a set retarding agent, or a set accelerating agent.

In a fifth aspect of the first example embodiment, the method is as described above with respect to the first through the fourth aspects of the first example embodiments, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid. In various aspects, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder. In one aspect, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder.

In a sixth aspect of the first example embodiment, the method is as described above with respect to the first through the fourth aspects of the first example embodiments, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set retarding agent. In various aspects, the strength enhancement agent is present in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder; the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder; the set retarding agent is added in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder. In other aspects, the strength enhancement agent is present in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder; the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder; the set retarding agent is added in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder.

In a seventh aspect of the first example embodiment, the method is as described above with respect to the first through the fourth aspects of the first example embodiments, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set accelerating agent. In various aspects, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001 to 0.06% based on dry weight of the hydraulic cementitious powder, the set accelerating agent is added in the amount of from 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder. In other aspects, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001 to 0.1% based on dry weight of the hydraulic cementitious powder, the set accelerating agent is added in the amount of from 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.

In an eighth aspect of the first example embodiment, the method is as described above with respect to the first through the fourth aspects of the first example embodiments, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid, a set retarding agent, and a set accelerating agent. In various aspects, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder, the set retarding agent is added in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the set accelerating agent is added in the amount of 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder. In other aspects, the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder, the set retarding agent is added in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the set accelerating agent is added in the amount of 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.

In a ninth aspect of the first example embodiment, the method is as described above with respect to any of the first through eighth aspects, and further the strength enhancing agent is N-(2-hydroxyethyl)iminodiacetic acid (EDG) or a salt thereof (e.g. sodium, potassium).

In a tenth aspect of the first example embodiment, the method is as described above with respect to any of the fourth through ninth aspects, and further the grinding aid is one or more of a glycol (e.g., diethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, tetra propylene glycol), glycerin, a C1-C6 alkanolamine (e.g., TEA, DEIPA, and TIPA), acetic acid or an acetic acid salt (e.g., sodium acetate).

In an eleventh aspect of the first example embodiment, the method is as described above with respect to the fourth through sixth and eighth and ninth aspects, and further the set retarding agent is one or more of a gluconate salt (e.g. sodium gluconate), a molasses, sucrose, or a corn syrup.

In a twelfth aspect of the first example embodiment, the method is as described above with respect to the fourth, fifth, seventh, eighth, and ninth aspects, and further the set accelerating agent is one or more of a thiocyanate salt (e.g. sodium, potassium, calcium) or a chloride salt (sodium, potassium, calcium).

In a thirteenth aspect of the first example embodiment, the method is as described above with respect to the fourth embodiment, and further the strength enhancing agent is EDG or a salt thereof (e.g. sodium, potassium), the grinding aid is the glycol (e.g., diethylene glycol, DEG), the set retarding agent is sodium gluconate, and the set accelerating agent is sodium thiocyanate.

In a fourteenth aspect of the first example embodiment, the method is as described above with respect to any of the aspects of the first example embodiment, further including grinding the cement clinker and the strength-enhancing agent with an alkali sulfate (e.g., sodium sulfate). In an additional aspect of the first example embodiment, the method is as described above with respect to any of the aspects of the first example embodiment, further including grinding the cement clinker and the strength-enhancing agent with an alkali sulfate and/or an alkali carbonate (e.g., sodium sulfate, sodium carbonate, sodium bicarbonate).

In a fifteenth aspect of the first example embodiment, the strength-enhancing agent is made by a process comprising: reacting a monohaloacetic acid chosen from monochloroacetic acid and monobromoacetic acid, or a salt thereof, with a alkanolamine chosen from ethanolamine, isopropanolamine, and isobutanolamine under alkaline conditions to generate the strength-enhancing agent represented by the structural formula

wherein: R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, represent —CH₂COOR*, where R* is defined above with respect to the first aspect of the first example embodiment. For example, the haloacetic acid or its salt is chloroacetic acid or its salt, and R¹ is —CH₂CH₂OH.

In any of aspects of the first example embodiment, the content of Na₂O equivalent in the hydraulic cementitious material is less than or equal to 0.7% by weight of the hydraulic cementitious powder. The content of Na₂O equivalents in cement is determined as follows, in weight percent: % Na₂O equivalent=% Na₂O+0.658*% K₂O, where the values of % Na₂O and % K₂O in cement can be determined using either X-ray fluorescence (XRF) or inductively coupled plasma mass spectroscopy (ICP-MS).

In a second example embodiment, the present invention is a composition prepared by the method of any one aspect of the first example embodiment.

In a third example embodiment, the present invention is an additive composition, comprising (A) a strength-enhancing agent represented by the following structural formula:

and (B) at least one grinding aid selected from one or more of a glycol (e.g., diethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, tetra propylene glycol), glycerin, or acetic acid or a salt thereof, wherein the additive composition is a liquid.

The strength-enhancing agent of the third example embodiment is described above with respect to the first example embodiment.

In a first aspect of the third example embodiment, the weight ratio of the strength enhancing agent to the grinding aid in the additive composition is from 1:9 to 9:1. In another aspect of the third example embodiment, the weight ratio of the strength enhancing agent to the grinding aid in the additive composition is from 1:19 to 19:1.

In the second aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, further comprising a set retarding agent, a set accelerating agent, or a mixture thereof.

In the third aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, and further the strength enhancing agent is N-(2-hydroxyethyl)iminodiacetic acid (EDG) or a salt thereof (e.g. sodium, potassium).

In the fourth aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, and further the at least one grinding aid is diethylene glycol.

In the fifth aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, further comprising sodium gluconate or sodium thiocyanate.

In the sixth aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, further comprising an alkali sulfate (e.g., sodium sulfate). In the another aspect of the third example embodiment, the additive composition is as described above with respect to any of the aspects of the second example embodiment, further comprising an alkali sulfate and/or an alkali carbonate (e.g., sodium sulfate, sodium carbonate, sodium bicarbonate).

In a fourth example embodiment, the present invention is a cementitious composition comprising a cementitious binder obtained by grinding a cement clinker with the additive composition of any aspect of the third example embodiment.

In a fifth example embodiment, the present invention is a cement composition, comprising a hydraulic cementitious powder, said hydraulic cementitious powder including tricalcium aluminate (C₃A) in an amount of from 0.3% to 9.0% based on dry weight of the hydraulic cementitious powder; a strength-enhancing agent, said strength-enhancing agent being present in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder, and at least one grinding aid selected from a glycol (e.g., diethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, tetra propylene glycol), glycerin, or acetic acid or an acetate salt (e.g., sodium or potassium acetate).

The strength-enhancing agent of the fifth example embodiment is described above with respect to the first example embodiment.

In a sixth example embodiment, the present invention is an additive composition for use in grinding with a cement clinker, said composition comprising (A) a strength-enhancing agent and (B) at least one grinding aid selected from one or more of a glycol, glycerin, or acetic acid or an acetate salt, wherein the additive composition is a liquid. The strength-enhancing agent of the sixth example embodiment is described above with respect to the first example embodiment.

In a seventh example embodiment, the present invention is a mixture of a cement clinker and the additive composition of any aspect of the third example embodiment.

In an eighth example embodiment, the present invention is a method for making a strength-enhancing agent, comprising reacting a haloacetic acid chosen from one or more of a chloroacetic acid and a bromoacetic acid, or a salt thereof, with one or more alkanolamines of the structural formula (I)

under alkaline conditions, to generate the strength-enhancing agent represented by structural formula (II)

wherein each R¹⁰ is independently chosen from H, (C₁-C₄)alkyl-OH, provided that in structural formula (I) at least one group R¹⁰ is not H; R²⁰ is chosen from (C₁-C₄)alkyl-OH, and —C(R⁴)₂COO⁻M⁺; and R³⁰ is —C(R⁴)₂COO⁻M⁺; each R⁴ is independently chosen from hydrogen, Br, and Cl; and M⁺is H⁺, Na⁺, K⁺, or ½ Ca⁺⁺.

In a first aspect of the eighth example embodiment, the chloroacetic acid is monochloracetic acid or a salt thereof; the compound represented by structural formula (I) is ethanolamine represented by the following structural formula HO—CH₂—CH₂—NH₂; and the strength-enhancing agent represented by structural formula (II) is sodium ethanol-diglycine (EDG)

wherein the monochloracetic acid or a salt thereof and the ethanolamine are reacted in the presence of sodium hydroxide at above room temperature.

In another aspect, the monochloracetic acid or a salt thereof and the ethanolamine are reacted in the presence of sodium hydroxide at any temperature at which the reaction process can be carried out, for example at or above room temperature. The temperature of reaction can be chosen depending on a particular condition to reduce the process of the present invention to practice. For example, when the higher productivity of the process is desirable, higher temperature, such as at above the room temperature can be chosen, whereas the higher EDG content is desired, the lower temperature, such as at the room temperature or below, is preferably applied. The temperature of the manufacturing process is suitably controlled depending on the preferences of the product and the production process. It is noted that the neutralization of chloroacetic acid with alkali generates heat that can either be used or controlled as the reaction temperature chosen above.

In a ninth example embodiment, the present invention is a strength-enhancing agent made by the methods according to the any aspect of the eighth example embodiment. It is contemplated that the strength enhancing agent according to the ninth example embodiment can be used in the methods and compositions according to any aspects of the first to the seventh example embodiments.

In a tenth example embodiment, the present invention is an additive composition, comprising a first component; and a cement additive component, wherein the cement additive component is one or more agent chosen from a glycol, glycerol, acetic acid or a salt thereof, an alkanolamine, an amine, a carbohydrate, a water-reducing additive, an air-entraining agent, a chloride salt, a nitrite salt, a nitrate salt, and a thiocyanate salt; and the first component is prepared according to the eighth example embodiment and any aspect thereof.

In a first aspect of the tenth example embodiment, the additive composition is in liquid form.

In an eleventh example embodiment, the present invention is a concrete composition, comprising the additive composition according to the tenth example embodiment and any aspect thereof; cement; a fine aggregate; a coarse aggregate, and at least one supplemental cementitious material chosen from fly ash, granulated blast furnace slag, limestone, calcined clay, natural pozzolan, and artificial pozzolan.

In a twelfth example embodiment, the present invention is a method of making a concrete composition, comprising preparing a reaction mixture according to the fifteenth aspect of the first example embodiment or the eight example embodiment and any aspect thereof, adding the reaction mixture without purification to a cement clinker; and grinding the cement clinker and the reaction mixture, thereby producing a hydraulic cementitious powder.

It has now been discovered that, unlike traditional strength-enhancers (e.g., TEA, DEIPA, TIPA), the strength-enhancing agents described herein (e.g., ethanol diglycinate in acid or salt form) do not involve increasing the solubility of iron in the hydrated cement, and, therefore do not cause yellow staining on finished products.

Other strength enhancing agents, such as TEA, DEIPA, and TIPA, while improving strength, tend to increase the amount of air entrained in the cement. In some instances, adding such agents can lead to set cement compositions with large porosity and poor finished surfaces. Although incorporation of air detraining agents (ADA), such as those illustrated in U.S. Pat. No. 5,156,679, incorporated herein by reference in its entirety, enable reduction in the air content, the formation and release of bubbles from the cement compositions cannot be eliminated.

The amino acid derivatives described herein can simultaneously improve early strength, without entraining large air voids. This is desirable as it can lead to cement compositions, such as Portland cement concrete, with lower porosities and better finished surfaces.

A particular advantage of the additive of the invention is that it may be either interground or intermixed with the cement. As used herein, the terms “interground” and “intermixed” refer to the particular stage of the cement processing in which the amino acid derivatives described herein, for example EDG, are added. They may be added to the clinker during the finish grinding stage and thus interground to help reduce the energy requirements and provide a uniform free flowing cement powder with reduced tendency to form lumps during storage. It is also possible to add the subject additives as an admixture to powdered cement either prior to, in conjunction with, or after the addition of water when effecting the hydraulic setting of the cement. Further, the amino acid derivatives of this invention may be supplied in a pure concentrated form, or diluted in aqueous or organic solvents, and may also be used in combination with other chemical admixtures, including but not limited to: accelerating admixtures, air entrainers, air detrainers, water-reducing admixtures, retarding admixtures (as defined in ASTM C494) and the like, and mixtures thereof. The additive according to the invention may be used with ordinary cement or with blended cements.

Example embodiments of the invention, including the strength-enhancing agents made by reacting a haloacetic acid or a salt thereof with an alkanolamine, provide additive compositions for facilitating cement grinding, and provide early cement strength enhancement, without generating the attendant disadvantages of producing hazardous products as would be expected from current commercial processes that involve monoethanolamine, formaldehyde, and sodium cyanide starting materials.

One skilled in the art, using the preceding detailed description, can utilize the present invention to its fullest extent. The following examples are provided to illustrate the invention, but should not be construed as limiting the invention in any way except as indicated in the appended claims. All parts and percentages are by weight unless otherwise indicated and additives are expressed as percent active ingredient as solids based weight of dry cement (% s/c). Compressive strengths of the cement samples were determined in accordance with EN method 196-1. The following examples were prepared using commercially available cements and clinkers.

EXEMPLIFICATION Example 1: Ethanoldiglycine Disodium Salt (Na₂-EDG) Enhances Early Strength of Cements

Table 1, presented in FIG. 4A and FIG. 4B, describes cement samples tested in this example.

A variety of cements (i.e. cementitious material) have been tested in mortars (i.e. the cement composition), and the impact of 0.02% Na2-EDG by weight of the cementitious material on compressive strength has been assessed. The content of the total crystalline phases has been determined by quantitative X-ray diffraction using Rietveld refinement method. The content of sulfur element, expressed as SO₃, was determined by X-ray fluorescence (XRF). The total alkali content or the content of Na₂O equivalent in cement is determined as follows, in weight percent: % Na₂O equivalent=% Na₂O+0.658*% K₂O, where the values of % Na₂O and % K₂O in cement are determined using XRF. The description of the tested cements and the results of the compressive strength measurements are provided in Table 1 (see FIGS. 4A and 4B).

Mortars were prepared following the EN 196-1 testing protocol, where 450 grams of cement are mixed with 225 grams of water and 1350 grams of a graded sand. Additives were added to the water before mortar mixing. The mortar prepared this way was used to cast 40×40×160 mm prismatic specimens that were submitted to compression until rupture after 1 day of curing in a moist room at 20.6° C. and more than 95% relative humidity. The rupture load was converted to compressive strength (in MPa).

The results of this experiment indicate that Na₂-EDG can increase the strength of cements.

To visualize the results, the value of percent early strength increase as a function of the C₃A content was plotted. FIG. 1 represents such a plot for Na₂-EDG added at 0.02% by weight of the cementitious material.

Example 2: Na₂-EDG Enhances Early Strength

The performance of Na₂-EDG was compared to that of other additives—Na-glycine, sarcosine, and Na₂-EDTA—using Cement A.

The structures of these additives are reproduced below:

The mortars were prepared using Cement A as described above in Example 1. The additives (Sarcosine, glycine, sodium salt, EDTA, disodium salt, and EDG disodium salt) were added in varying amounts expressed as parts-per-million of the carboxylic groups (COO—), and the compressive strength of samples at Day 1 was measured. The results, presented as a plot of Day 1 compressive strength as a function of COO— content, are shown in FIG. 2A.

FIG. 2A shows that EDG is a superior enhancer of early strength when compared to the other additives.

The performance of EDG was further compared to that of bicine and TEA using Cement B. The structural formulas of bicine and TEA are reproduced below:

Mortars were prepared using Cement B as described above. The mortar mixes were used to prepare 40×40×160 mm prismatic specimens that were tested under compression load until rupture after 24 hours of storage at 20.6° C. and greater than 95% relative humidity.

FIG. 2B is a plot of Day 1 compressive strength (in MPa) of Cement B as a function of the content of the additive (in weight percent). FIG. 2B shows that 0.005%, 0.01% and 0.02% Na₂-EDG increased the 1-day strength of the cement by 0.8 MPa, 1.6 MPa, and 2.0 MPa, respectively. Bicine, added at 0.002% to 0.0075%, enhanced 1 day strength by 1.2 to 2.1 MPa, respectively. TEA added at 0.0075% and 0.015% enhanced 1 day strength by 1.9 MPa and 1.5 MPa, respectively. It is surprising that EDG had similar to superior performance to bicine and TEA, even though it contains two carboxyl groups.

Example 3: Na₂-EDG Improves Grinding Efficiency of Cements

The effect of Na₂-EDG additive on grinding efficiency of cementitious material was investigated in a laboratory scale ball mill. For this investigation, 3325 grams of a commercial clinker were ground in with 63.5 grams gypsum and 39.4 grams basanite (calcium sulfate hemi-hydrate) at 88-95° C. The grindings were periodically interrupted to evaluate the fineness of the cements using the Blaine air permeability apparatus, which allows assessing the specific surface area (SSA) of powders. Table 2, below, shows the Blaine SSA values for samples containing either no chemical additive or for samples containing 0.02% Na₂-EDG (% weight of solids on cement). In this experiment, 0.05% water (% of cement weight) was added to the control cementitious material (no chemical additive) to account for the presence of water in the EDG additive.

TABLE 2 Blaine specific surface area values of laboratory ground cements Blaine SSA Dosage (cm²/g) for each grinding time (minutes) Additive (% s/c) 120 150 210 250 295 325 347 None 0.00 2173 n/a 2474 n/a 2838 n/a 2958 EDG 0.02 2333 2562 2799 2893 3017 3050 n/a n/a: result not available

The data in Table 2 demonstrates that addition of Na₂-EDG increased the specific surface area of the ground material at all grinding times comparing to the sample with no chemical additives.

The particle size distributions (PSD) of the sample of the cementitious material to which 0.02% by weight Na₂-EDG was added, ground for 325 minutes, and of the sample containing no chemical additives, ground for 347 minutes, was determined using laser diffraction. This technique measures the particle size distribution by measuring the angular variation in intensity of light scattered as a laser beam passes through the dispersed powders. The data is presented in FIG. 3, which is a plot of “percent volume fraction” as a function of particle size in micrometers (i.e. the curve indicates the accumulated percent by volume at a given size in the sample). The tests were performed in a Malvern Mastersize 3000 particle size analyzer coupled with an Aero S dry dispersion unit in 1-3 grams cement samples.

It is seen that, even though ground for less time than the sample with no chemical admixtures, the curve representing the EDG sample is slightly shifted to lower particle sizes, indicating a finer distribution as compared to the sample with no chemical additives.

Example 4: Formulations with EDG Provide Higher Early Strength

Table 3 shows the impact of Na₂-EDG and combinations of Na₂-EDG with sodium thiocyanate, sodium gluconate, and/or diethylene glycol on the early strength of mortars prepared according to the protocol described in Example 1. Cement I was used to prepare the mortars. Table 3 shows that the combination of Na₂-EDG with other components allow a further increase of 1-day strength.

TABLE 3 Na- EDG NaSCN gluconate DEG 1 d % (% s/c) (% s/c) (% s/c) (% s/c) blank 0 0 0 0 100.0% 0.01 0 0 0 106.3% 0.02 0 0 0 108.4% 0.01 0.02 0.0075 0 111.3% 0.02 0.04 0 0 113.2% 0.02 0.04 0.015 0 122.1% 0.01 0 0 0.03 103.6% 0.02 0 0.015 0 103.4% 0.0077 0.02 0.0039 0.015 118.8% 0.0116 0.03 0.058 0.0225 124.8% 0.0155 0.04 0.078 0.03 126.5%

Table 4 shows the impact of Na₂-EDG and combinations with calcium chloride on the 1-day strength of mortars prepared according to the same protocol, using Cement E. The combination of Na₂-EDG with calcium chloride allows a further increase of 1-day compressive strength.

TABLE 4 EDG CaCl2 1 d % (% s/c) (% s/c) blank 0 0 100.0% 0 0.03 108.8% 0 0.06 122.8% 0.01 0 112.7% 0.01 0.03 123.2% 0.02 0 118.2% 0.02 0.06 127.6%

Example 5: Addition of EDG Causes No Iron Staining

A test to evaluate iron staining of mortars was conducted.

Cement W was weighed (259 g) and deposited in a plastic cylinder; sand was then added (1350 g) and the cylinder was manually and vigorously shaken for 30 seconds to allow the two components to blend. For mixes requiring the use of EDG, previously prepared mix water solutions were added to the Hobart mortar mixing bowl at this time; otherwise, the necessary amount of water (192 g) was weighed and added to the bowl. All samples had the same water-to-cement weight ratio of 0.74. The cement and sand blend was poured onto the water (or additive-containing water) in the bowl. The mixer was turned on and mixed at its lowest speed for 30 seconds, and then it was switched to its second lowest speed and allowed to mix for an additional 30 seconds. After this time, the mixer was stopped, the paddle and bowl were removed, and the mortar was stirred slightly in two revolutions with a spoon before being deposited (approximately 400 g) in a pre-labeled plastic bag. This bag was closed in such a way that all possible air was squished out. The bag was transported to an environmentally controlled room (54% relative humidity, 24° C.) with minimal traffic and allowed to sit for 7 days. After this time, a razor was used to make a slit in the bag (approximately 2 cm) near each corner, and the bag was allowed to sit for an additional 21 days in the controlled environment. At the end of this aging period, the region where the slits were cut were visually analyzed and photographed to document the findings related to iron staining. Yellow staining is defined as a yellow to orange shade to the mortar surface in the immediate vicinity of the cut slits. Samples containing no chemical admixtures (reference) and 0.02% Na₂-EDG (% cement weight) were prepared according to the above protocol, and no difference in color between the two samples were noticed, indicating that EDG does not cause yellow staining in finished products.

Example 6: Process for Making New Additive Compositions

This example describes the synthesis of ethylene-diglycine (EDG) by reacting mono-ethanolamine (MEA) with monochloracetic acid (MCA) in the presence of a sodium hydroxide (NaOH) and heat, to generate EDG and sodium chloride (NaCl).

The reaction products reported in Examples 6 through 18 included NaCl, a known strength enhancer, at 55-95% by weight of Na₂-EDG. The content of NaCl can be reduced to 0% by purification.

The reaction products reported in Examples 6 through 18 included impurities (i.e. compounds other than EDG and NaCl) at up to 12% of sample weight. The content of solid impurities was up to 40% of total solids in the reaction product mixture. The content of impurities can be reduced by optimizing the manufacturing process.

The synthesis was conducted by the following procedure: 10.91 g ethanolamine (0.175 moles), 56.01 g of 50% NaOH solution (0.700 moles) and 100 g of distilled water were charged into a 250 ml four neck round bottom flask. The flask was equipped with a condenser, a mechanical stirrer and a dropping funnel. Chloroacetic acid 33.08 g (0.350 moles) was dissolved in 24 grams of water and charged into the dropping funnel. Chloroacetic acid was slowly added to the flask over a period of 7 minutes. The reaction was then heated to a temperature of 90 degrees centigrade and held at that temperature for 5 hours. Additional 28.06 grams of 50% NaOH solution was added to complete the conversion of chloroacetic acid over the course of the reaction. The pH of the final product was 12.6.

Table 5 shows the early strengths (at Day 1) of mortars prepared with cements E, F, and I, described in FIG. 4A and FIG. 4B, in the presence of the informed percentages (% weight of solids and % weight of Na₂-EDG on cement weight or % s/c) of a commercial Na₂-EDG-based product manufactured by the process that involves monoethanolamine, formaldehyde, and sodium cyanide starting materials (named ‘commercial’) and of a product manufactured in the laboratory by combining MEA with MCA in the presence of NaOH. Table 5 shows the similar performance of the Example 6 sample compared to the ‘commercial’ sample.

TABLE 5 Dosage of solid reaction products Na₂—EDG Cement Source of EDG (% s/c) (% s/c) 1 d % blank E — 0 100.0% E Commercial 0.005 0.005 106.0% E Commercial 0.01 0.01 119.6% E Commercial 0.02 0.02 107.8% E Example 6 0.009 0.0059 112.1% E Example 6 0.017 0.0118 119.0% E Example 6 0.035 0.0236 117.0% F — 0 0 100.0% F Commercial 0.005 0.005 115.0% F Commercial 0.01 0.01 117.8% F Commercial 0.02 0.02 118.2% F Example 6 0.007 0.0044 113.6% F Example 6 0.015 0.0088 120.0% F Example 6 0.029 0.0177 126.1% I — 0 0 100.0% I Commercial 0.005 0.005 105.3% I Commercial 0.01 0.01 107.7% I Commercial 0.02 0.02 107.3% I Example 6 0.007 0.0044 114.4% I Example 6 0.015 0.0088 109.8% I Example 6 0.029 0.0177 110.2%

Table 6 shows the characterization of these two sources of EDG (‘commercial’ or Sample A, and ‘Example 6’ or Sample B). Total solids was calculated by a standard oven method by determining the weight difference after drying the sample at 125±1° C. for 25±1 minutes, run in triplicates. EDG material was tested for its chloride content by Ion Chromatography with the column for anions analysis with autosupressor and electrochemical detection (Dionex DX-500).

Structure analysis of EDG material was performed by H1 liquid-state Nuclear Magnetic Resonance Spectroscopy (Varian Unity INOVA 400 High resolution). FIG. 5 shows the NMR spectra of the two samples. NMR assignments (in ppm) are as follows: 2.71 (A), 2.74 (B) —NCH2-groups; 3.21 (A), 3.24 (B) Glycine —CH2-groups; 3.63 (A), 3.62 (B) —OCH2-groups.

The small differences in chemical shift between the two samples are due to differences in pH. Both samples show the major component is Na₂-EDG. Minor components are disodium ethanol monoglycinate and unidentified components.

TABLE 6 Commercial EDG or Example 6 EDG or Characteristic Sample A Sample B Total solids (%) 30.41 ± 0.07 27.56 ± 0.09 pH 12.97 12.60 Chloride (% of sample) 1.006 5.230

Examples 7-11—Synthesis of Na₂-EDG

The MCA-MEA adducts were prepared by the same process as described in Example 6. Table 7 shows the amounts of MCA, MEA and alkali used for the reactions. The final products pH values are also shown.

TABLE 7 Chloroacetic acid Ethanolamine Product (MCA) (MEA) Alkali addition pH Example 7 0.225 mol 0.113 mol Na₂CO₃ powder 9.8 (19553-186)  (21.3 grams)  (7.02 grams) 0.676 mol (71.67 grams) Example 8 0.350 mol 0.175 mol 50% NaOH solution 12.9 (19553-188) (33.08 grams) (10.91 grams) 1.61 mol NaOH (90.01 grams solution)* Example 9 0.350 mol 0.175 mol 50% NaOH solution 10.8 (19553-189) (33.08 grams) (10.91 grams)  0.7 mol NaOH (56.01 grams solution) Example 10 0.350 mol 0.175 mol NaOH pellet 3.3 (19553-190) (33.08 grams) (10.91 grams) 0.35 mol NaOH (14.00 grams solution) Example 11 0.350 mol 0.183 mol NaOH pellet NA (19553-191) (33.08 grams) (11.43 grams)  0.7 mol NaOH (28.01 grams solution) *0.7 mol (56.01 grams of 50% solution) of NaOH is added first, then 34 grams of 50% NaOH solution was added during the course of the reaction. NA: not available

Example 12-18—Synthesis and Performance of Na₂-EDG

The MCA-MEA adducts shown in Table 8 were prepared by similar process as described in Example 6 but under different temperatures and reaction times. Total solids was calculated by a standard oven as described in Example 6, and EDG content was determined by Ion Chromatography (IC). Set up for IC is Dionex DX-500 with column for anions analysis with auto-suppressor. EDG standard (acid form) at different concentrations was run to acquire calibration curve and, based on that, the amount of EDG (acid form) in the sample was calculated and recalculated to sodium salt form.

Table 9 shows the strength performance at 1 day of age of Examples 12-18 when tested in EN-196 mortars prepared with Cement F. Examples 12-18 show similar to superior performance compared to the ‘commercial’ sample.

TABLE 8 Theoretical Na₂-EDG Yield (mass %, Nominal Molar based on Na2- EDG Yield Ratio Reaction Reaction reactor EDG (% of (MCA:MEA:NaOH) T (° C.) time (h) charges) (%) theoretical) Example 2:1:4 60 1 19.0% 14.60 77 12 0060-27 Example 2:1:6 60 0.5 15.5% 10.38 67 13 0060-33 Example 2:1:6 50 1 15.5% 12.34 80 14 0060-39 Example 2:1:6 40 4 15.5% 9.87 64 15 0060-41 Example 2:1:4 40 4 19.0% 12.49 66 16 0060-43 Example 2:1:4 50 2 16.6% 14.70 89 17 0060-45 Example 2:1:4 25 n/a 19.0% 15.42 81 18 0060-49

TABLE 9 Dosage of solid reaction products 1 d % Source of EDG (% s/c) blank — 0 100.00%  Commercial 0.01 114.9% Commercial 0.02 116.3% Example 12 0.01 115.6% Example 12 0.02 124.4% Example 13 0.01 113.8% Example 13 0.02 118.5% Example 14 0.01 113.6% Example 14 0.02 116.7% Example 15 0.01 115.6% Example 15 0.02 119.4% Example 16 0.01 125.0% Example 16 0.02 121.7% Example 17 0.01 113.9% Example 17 0.02 118.2% Example 18 0.01 127.3% Example 18 0.02 126.9%

Example 19: Formulation with EDG and Diethanolisopropanolamine (DEIPA) Provides Higher Early Strength than Formulations with Just One of these Amines

A combination of EDG, diethanolisopropanolamine (DEIPA), and calcium chloride was evaluated for its ability to enhance either early strength, or late strength, or both of a cement. The Example 19 Cement was used to prepare the mortars. The results of the QXRD and XRF analyses of the Example 19 cement are presented below in Tables 10 and 11.

TABLE 10 QXRD analysis of Example 19 Cement Phase determined by % QXRD weight Alite 66.2 Belite 9.9 C4AF 11.0 C3A 4.3 CaO 0.1 MgO 1.0 Ca(OH)2 0.6 Calcite 0.9 Gypsum 2.6 Hemihydrate 0.0 Anhydrite 2.5

TABLE 11 XRF analysis of Example 19 Cement Analyte determined by XRF Weight % Total SO₃ 2.71 Total Alkali 0.47

The mortars were prepared according to the protocol described in Example 1 using the Example 19 Cement, and the results of strength measurements were expressed as a change in MPa compared to a reference cement (DMPa). The results are presented in Table 12.

TABLE 12 Strength of Example 19 Cement EDG DEIPA CaCl₂ DMPa DMPa DMPa Total Run ppm ppm ppm 1 day 3 day 7 day DMPa Avg DMPa 1 118 0 293 0.6 1 0.7 2.3 0.76 2 0 100 293 1.2 0.5 −0.7 1.0 0.33 3 50 58 293 1.0 1.0 1.5 3.5 1.17

Runs 1 and 2 reported in Table 12 were done with either EDG or DEIPA alone, and resulted in the average strength increase (“Avg DMPa”) of 0.76 and 0.33 MPa, respectively. Run 3 was done using a blend of EDG and DEIPA at similar total dosage. The average strength increase was 1.17 MPa.

While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 

1. A method of making a cement composition, comprising: grinding a cement clinker and a strength-enhancing agent, thereby producing a hydraulic cementitious powder, wherein: the strength-enhancing agent is present in the hydraulic cementitious powder in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder, the strength-enhancing agent is a compound represented by the following structural formula:

wherein: R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, is (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺.
 2. The method of claim 1, further including adding to the cement clinker at least one supplemental cementitious material selected from the group consisting of: fly ash, granulated blast furnace slag, limestone, calcined clay, natural pozzolan and artificial pozzolan.
 3. The method of claim 1, wherein the cement clinker includes C₃A in an amount of 0.3% to 9.0% based on dry weight of cement clinker.
 4. The method of claim 1, further comprising grinding with the strength enhancement agent and the cement clinker at least one supplemental component selected from a grinding aid, a set retarding agent, or a set accelerating agent.
 5. The method of claim 1, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid, and further wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder.
 6. The method of claim 1, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set retarding agent, wherein: the strength enhancement agent is present in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder; the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder; the set retarding agent is added in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder.
 7. The method of claim 1, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set accelerating agent, wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001 to 0.06% based on dry weight of the hydraulic cementitious powder, the set accelerating agent is added in the amount of from 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.
 8. The method of claim 1, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid, a set retarding agent, and a set accelerating agent, wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001% to 0.06% based on dry weight of the hydraulic cementitious powder, the set retarding agent is added in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the set accelerating agent is added in the amount of 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.
 9. The method of claim 5, wherein the grinding aid is one or more of a glycol, glycerin, alkanolamine, acetic acid or an acetic acid salt.
 10. The method of claim 6, wherein the set retarding agent is one or more of a gluconate salt, a molasses, sucrose, or a corn syrup.
 11. The method of claim 7, wherein the set accelerating agent is one or more of a thiocyanate salt or a chloride salt.
 12. (canceled)
 13. The method of claim 4 wherein the strength enhancing agent is EDG or a salt thereof, the grinding aid is the glycol, the set retarding agent is sodium gluconate, and the set accelerating agent is sodium thiocyanate.
 14. The method of claim 1, further including grinding the cement clinker and the strength-enhancing agent with an alkali sulfate.
 15. The method of claim 1, wherein the content of Na₂O equivalent in the hydraulic cementitious material is less than or equal to 0.7% by weight of the hydraulic cementitious powder.
 16. A composition prepared by the method of claim
 1. 17. An additive composition, comprising: (A) a strength-enhancing agent represented by the following structural formula:

wherein: R¹ is a (C₁-C₄)alkyl-OH; and R² and R³, each independently, is a (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺; and (B) at least one grinding aid selected from one or more of a glycol, glycerin, or acetic acid or an acetic acid salt, wherein the additive composition is a liquid.
 18. The additive composition of claim 17, wherein the weight ratio of the strength enhancing agent to the grinding aid is from 1:9 to 9:1.
 19. The additive composition of claim 17, further comprising a set retarding agent, a set accelerating agent, or a mixture thereof.
 20. The additive composition of claim 17, wherein the strength enhancing agent is N-(2-hydroxyethyl)iminodiacetic acid (EDG) or a salt thereof.
 21. The additive composition of claim 17, wherein the at least one grinding aid is diethylene glycol.
 22. The additive composition of claim 17, further comprising sodium gluconate or sodium thiocyanate.
 23. The additive composition of claim 17, further comprising an alkali sulfate.
 24. A cementitious composition comprising a cementitious binder obtained by grinding a cement clinker with the additive composition of claim
 17. 25. A cement composition, comprising: a hydraulic cementitious powder; a strength-enhancing agent, said strength-enhancing agent being present in an amount of from 0.001% to 0.09% based on dry weight of the hydraulic cementitious powder, wherein the strength-enhancing agent is a compound represented by the following structural formula:

wherein: R¹ is a (C₁-C₄)alkyl-OH; and R² and R³, each independently, is a (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺; and at least one grinding aid selected from a glycol, glycerin, or acetic acid or an acetic acid salt.
 26. An additive composition for use in grinding with a cement clinker, said composition comprising: (A) a strength-enhancing agent represented by the following structural formula:

wherein: R¹ is a (C₁-C₄)alkyl-OH; and R² and R³, each independently, is a (C₀-C₃)alkyl-COOR*, wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺; and (B) at least one grinding aid selected from one or more of a glycol, glycerin, or acetic acid or a salt thereof, wherein the additive composition is a liquid.
 27. A mixture of a cement clinker and the additive composition of claim
 17. 28. A method of claim 1, wherein the strength-enhancing agent is made by a process comprising: reacting a monohaloacetic acid chosen from monochloroacetic acid and monobromoacetic acid, or a salt thereof, with a alkanolamine chosen from ethanolamine, isopropanolamine, and isobutanolamine under alkaline conditions to generate the strength-enhancing agent represented by the structural formula

wherein: R¹ is (C₁-C₄)alkyl-OH; R² and R³, each independently, represent —CH₂COO⁻R*, and R* is H, Na⁺, K⁺, or ½ Ca⁺⁺.
 29. The method of claim 28, wherein the haloacetic acid or its salt is chloroacetic acid or its salt, and R¹ is —CH₂CH₂OH.
 30. A method for making a strength-enhancing agent, comprising: reacting a haloacetic acid chosen from one or more of a chloroacetic acid and a bromoacetic acid, or a salt thereof, with one or more alkanolamines of the structural formula (I)

under alkaline conditions, to generate the strength-enhancing agent represented by structural formula (II)

wherein: each R¹⁰ is independently chosen from H, (C₁-C₄)alkyl-OH, provided that in structural formula (I) at least one group R¹⁰ is not H; R²⁰ is chosen from (C₁-C₄)alkyl-OH, and —C(R⁴)₂COO⁻M⁺; and R³⁰ is —C(R⁴)₂COO⁻M⁺; each R⁴ is independently chosen from hydrogen, Br, and Cl; and M⁺ is H⁺, Na⁺, K⁺, or ½ Ca⁺⁺.
 31. The method of claim 30, wherein: the chloroacetic acid is monochloracetic acid or a salt thereof; the compound represented by structural formula (I) is ethanolamine represented by the following structural formula HO—CH₂—CH₂—NH₂; and the strength-enhancing agent represented by structural formula (II) is sodium ethanol-diglycine

wherein the monochloracetic acid or a salt thereof and the ethanolamine are reacted in the presence of sodium hydroxide at above room temperature.
 32. A strength-enhancing agent made by the methods according to claim
 28. 33. An additive composition, comprising: a first component; and a cement additive component wherein: the cement additive component is one or more agents chosen from a glycol, glycerol, acetic acid or a salt thereof, an alkanolamine, an amine, a carbohydrate, a water-reducing additive, an air-entraining agent, a chloride salt, a nitrite salt, a nitrate salt, and a thiocyanate salt; and the first component is prepared by reacting a haloacetic acid chosen from one or more of a chloroacetic acid and a bromoacetic acid, or a salt thereof, with one or more alkanolamines of the structural formula (I)

under alkaline conditions, to generate the first component represented by structural formula (II)

wherein: each R¹⁰ is independently chosen from H, (C₁-C₄)alkyl-OH, provided that in structural formula (I) at least one group R¹⁰ is not H; R²⁰ is chosen from (C₁-C₄)alkyl-OH, and —C(R⁴)₂COO⁻M⁺; and R³⁰ is —C(R⁴)₂COO⁻M⁺; each R⁴ is independently chosen from hydrogen, Br, and Cl; and M⁺ is H⁺, Na⁺, ½ Ca⁺⁺.
 34. The additive composition of claim 33, wherein: the chloroacetic acid is monochloracetic acid or a salt thereof; the compound represented by structural formula (I) is ethanolamine represented by the following structural formula HO—CH₂—CH₂—NH₂; and the strength-enhancing agent represented by structural formula (II) is sodium ethanol-diglycine

wherein the monochloracetic acid or a salt thereof and the ethanolamine are reacted in the presence of sodium hydroxide at above room temperature.
 35. The additive composition of claim 33, wherein the additive composition is in liquid form.
 36. A concrete composition, comprising: the additive composition of claim 33, cement; a fine aggregate; a coarse aggregate, and at least one supplemental cementitious material chosen from fly ash, granulated blast furnace slag, limestone, calcined clay, natural pozzolan, and artificial pozzolan.
 37. A method of making a cement composition, comprising: reacting a monohaloacetic acid chosen from monochloroacetic acid and monobromoacetic acid, or a salt thereof, with a alkanolamine chosen from ethanolamine, isopropanolamine, and isobutanolamine under alkaline conditions to generate the strength-enhancing agent represented by the structural formula

wherein: R¹ is (C₁-C₄)alkyl-OH; and R² and R³, each independently, represent —CH₂COO⁻R*, wherein R* is H, Na⁺, K⁺, or ½ Ca⁺⁺ thereby preparing a reaction mixture; adding the reaction mixture without purification to a cement clinker; and grinding the cement clinker and the reaction mixture, thereby producing a hydraulic cementitious powder.
 38. The method of claim 4, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid, and further wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder.
 39. The method of claim 4, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set retarding agent, wherein: the strength enhancement agent is present in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder; the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder; the set retarding agent is added in the amount of 0.001-0.03% based on dry weight of the hydraulic cementitious powder.
 40. The method of claim 4, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid and a set accelerating agent, wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001 to 0.1% based on dry weight of the hydraulic cementitious powder, the set accelerating agent is added in the amount of from 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.
 41. The method of claim 4, further comprising grinding with the strength enhancement agent and the cement clinker at least one grinding aid, a set retarding agent, and a set accelerating agent, wherein: the strength enhancement agent is present in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, the at least one grinding aid is added in the amount of from 0.001% to 0.1% based on dry weight of the hydraulic cementitious powder, the set retarding agent is added in the amount of from 0.001% to 0.03% based on dry weight of the hydraulic cementitious powder, and the set accelerating agent is added in the amount of 0.001% to 0.2% based on dry weight of the hydraulic cementitious powder.
 42. The method of claim 1, further including grinding the cement clinker and the strength-enhancing agent with an alkali sulfate and/or an alkali carbonate.
 43. (canceled)
 44. (canceled)
 45. (canceled)
 46. (canceled)
 47. (canceled)
 48. (canceled)
 49. (canceled)
 50. (canceled)
 51. (canceled)
 52. (canceled) 